1. Field of the Invention
This invention relates to an endoscope apparatus whereby a color picture image in a general visible range and a special picture image by a combination of specific wavelength range can be observed.
2. Related Art Statement
Recently, there is extensively utilized an endoscope whereby an organ within a body cavity or the like can be observed by inserting an elongate insertable part into a cavity of a living body or mechanical component part or, as required, various curing treatments can be made by using a treating tool inserted through a treating tool channel.
Also, there are suggested various electronic endoscopes wherein such solid state imaging device as a change coupled device (CCD) is used for an imaging means.
Now, in case an object is to be observed by using the above mentioned endoscope and particularly, in case an affected part and a normal part are to be distinguished from each other within a living body, it will be necessary to sense (recognize) a delicate tone difference. However, in case the tone variation in the observed part is delicate, a high knowledge and experience will be required to sense this delicate difference and further a long time will be required until it is sensed and, even if attentions are concentrated while sensing, it has been difficult to always judge properly.
In order to cope with these problems, conventionally, for example, as shown in the publication of a Japanese patient application laid open No. 30331 1981, by utilizing the peculiarity of a living body in an infrared light range, for example, the fact that the variation of the tone is larger in the infrared light range, a color separating filter in a visible light range to an infrared light range is provided on the front surface of a solid state imaging device to make it possible to detect an affected part which has been difficult to sense only in the visible light range.
The infrared light is known to be easy to penetrate within a living body. By observing with an infrared light, such tissue interior as, for example, the blood flow within the vein below the mucous membrane or the minute structure of the vein can be observed.
However, in the above mentioned prior art example, there is a problem that, as the observing wavelength range is fixed, for example, in the case of the observation by utilizing an infrared light, a picture image in the general visible light range will not be obtained and therefore it will be difficult to compare both picture images.
There are also problems that, when a filter in an infrared light range is combined with a color separating filter in a visible light range, the respective pixels of the visible light range picture image and infrared light range picture image will reduce, that is, the resolution will reduce and that, in a frame sequential system wherein a color picture image is obtained by inputting a light of a wavelength range difference in time series, if many filters are provided in a visible light range to an infrared light range, the respective aperture rates will reduce, therefore the light amount will reduce and the sensitivity will reduce.
It is also known that knowing the amount of hemoglobin and the distribution of oxygen saturation degrees in a blood serves to early discover a disease. As a method of determining the amount of hemoglobin and the oxygen saturation degree in a blood, for example, as shown in the publication of a Japanese utility model application laid open No. 151705/1986, there is a method wherein they are determined from picture images in a plurality of specific wavelength ranges related to hemoglobin in the blood.
However, with the camera shown in the above mentioned prior art example, as the observed wavelength range is fixed, generally a color picture image in a visible range can not be obtained and, for example, a special picture image containing an information of a blood and a picture image in a general visible range can not be compared with each other.
By the way, in U.S. Pat. No. 4,717,952, there is disclosed an apparatus whereby a color picture image in a visible range and a picture image in a near infrared range can be observed. However, in this prior art example, the picture image in the near infrared range is a monochromatic picture image by one wavelength range and the amount of hemoglobin and the oxygen saturation degree in a blood can not be thereby known.